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	$141.63	6.793%	$151.2509	$151.25	$151.25	$151.30
Purchase #2	$126.77	3.472%	$131.1715	$131.17	$131.15	$131.20
Purchase #3	$167.31	11.136%	$185.9416	$185.94	$185.95	$185.90
Purchase #4	$65.77	5.183%	$69.1789	$69.18	$69.20	$69.20
Purchase #5	$131.92	3.552%	$136.6058	$136.61	$136.60	$136.60
Purchase #6	$246.59	9.780%	$270.7065	$270.71	$270.70	$270.70
Purchase #7	$144.66	5.108%	$152.0492	$152.05	$152.05	$152.00
7 purchase totals =	$1,024.65		$1,096.9044	$1,096.91	$1,096.90	$1,096.90