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	$203.53	4.123%	$211.9215	$211.92	$211.90	$211.90
Purchase #2	$6.91	4.367%	$7.2118	$7.21	$7.20	$7.20
Purchase #3	$209.59	5.464%	$221.042	$221.04	$221.05	$221.00
Purchase #4	$236.44	6.819%	$252.5628	$252.56	$252.55	$252.60
Purchase #5	$223.98	13.852%	$255.0057	$255.01	$255.00	$255.00
Purchase #6	$56.59	4.342%	$59.0471	$59.05	$59.05	$59.00
Purchase #7	$90.30	13.510%	$102.4995	$102.50	$102.50	$102.50
7 purchase totals =	$1,027.34		$1,109.2904	$1,109.29	$1,109.25	$1,109.20