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	$161.76	3.499%	$167.42	$167.42	$167.40	$167.40
Purchase #2	$89.26	11.644%	$99.6534	$99.65	$99.65	$99.70
Purchase #3	$220.93	3.145%	$227.8782	$227.88	$227.90	$227.90
Purchase #4	$136.51	6.846%	$145.8555	$145.86	$145.85	$145.90
Purchase #5	$114.42	7.621%	$123.1399	$123.14	$123.15	$123.10
Purchase #6	$119.53	3.830%	$124.108	$124.11	$124.10	$124.10
Purchase #7	$218.76	8.395%	$237.1249	$237.12	$237.10	$237.10
7 purchase totals =	$1,061.17		$1,125.1799	$1,125.18	$1,125.15	$1,125.20