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	$87.55	10.168%	$96.4521	$96.45	$96.45	$96.50
Purchase #2	$118.84	12.109%	$133.2303	$133.23	$133.25	$133.20
Purchase #3	$100.85	13.403%	$114.3669	$114.37	$114.35	$114.40
Purchase #4	$232.49	7.602%	$250.1639	$250.16	$250.15	$250.20
Purchase #5	$243.40	4.740%	$254.9372	$254.94	$254.95	$254.90
Purchase #6	$55.45	11.426%	$61.7857	$61.79	$61.80	$61.80
Purchase #7	$245.91	11.470%	$274.1159	$274.12	$274.10	$274.10
7 purchase totals =	$1,084.49		$1,185.0520	$1,185.06	$1,185.05	$1,185.10