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	$69.36	3.450%	$71.7529	$71.75	$71.75	$71.80
Purchase #2	$172.38	13.771%	$196.1184	$196.12	$196.10	$196.10
Purchase #3	$37.53	5.279%	$39.5112	$39.51	$39.50	$39.50
Purchase #4	$101.51	3.560%	$105.1238	$105.12	$105.10	$105.10
Purchase #5	$170.81	5.701%	$180.5479	$180.55	$180.55	$180.50
Purchase #6	$175.91	11.445%	$196.0429	$196.04	$196.05	$196.00
Purchase #7	$224.25	7.666%	$241.441	$241.44	$241.45	$241.40
7 purchase totals =	$951.75		$1,030.5381	$1,030.53	$1,030.50	$1,030.40