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	$157.65	3.301%	$162.854	$162.85	$162.85	$162.90
Purchase #2	$148.34	11.626%	$165.586	$165.59	$165.60	$165.60
Purchase #3	$75.65	13.424%	$85.8053	$85.81	$85.80	$85.80
Purchase #4	$84.95	3.869%	$88.2367	$88.24	$88.25	$88.20
Purchase #5	$223.93	9.283%	$244.7174	$244.72	$244.70	$244.70
Purchase #6	$242.65	13.585%	$275.614	$275.61	$275.60	$275.60
Purchase #7	$162.47	3.577%	$168.2816	$168.28	$168.30	$168.30
7 purchase totals =	$1,095.64		$1,191.0950	$1,191.10	$1,191.10	$1,191.10