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	$209.26	3.273%	$216.1091	$216.11	$216.10	$216.10
Purchase #2	$151.62	10.425%	$167.4264	$167.43	$167.45	$167.40
Purchase #3	$30.61	9.631%	$33.558	$33.56	$33.55	$33.60
Purchase #4	$69.47	3.552%	$71.9376	$71.94	$71.95	$71.90
Purchase #5	$233.44	9.184%	$254.8791	$254.88	$254.90	$254.90
Purchase #6	$79.28	5.459%	$83.6079	$83.61	$83.60	$83.60
Purchase #7	$240.51	11.244%	$267.5529	$267.55	$267.55	$267.60
7 purchase totals =	$1,014.19		$1,095.0710	$1,095.08	$1,095.10	$1,095.10