Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$184.44	8.657%	$200.407	$200.41	$200.40	$200.40
Purchase #2	$139.87	13.575%	$158.8574	$158.86	$158.85	$158.90
Purchase #3	$228.76	9.343%	$250.133	$250.13	$250.15	$250.10
Purchase #4	$203.83	9.808%	$223.8216	$223.82	$223.80	$223.80
Purchase #5	$226.50	7.398%	$243.2565	$243.26	$243.25	$243.30
Purchase #6	$109.61	13.835%	$124.7745	$124.77	$124.75	$124.80
Purchase #7	$224.32	7.842%	$241.9112	$241.91	$241.90	$241.90
7 purchase totals =	$1,317.33		$1,443.1612	$1,443.16	$1,443.10	$1,443.20