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	$164.25	5.708%	$173.6254	$173.63	$173.65	$173.60
Purchase #2	$96.56	3.181%	$99.6316	$99.63	$99.65	$99.60
Purchase #3	$128.53	11.772%	$143.6606	$143.66	$143.65	$143.70
Purchase #4	$93.80	5.642%	$99.0922	$99.09	$99.10	$99.10
Purchase #5	$146.52	5.631%	$154.7705	$154.77	$154.75	$154.80
Purchase #6	$196.57	5.270%	$206.9292	$206.93	$206.95	$206.90
Purchase #7	$226.95	3.158%	$234.1171	$234.12	$234.10	$234.10
7 purchase totals =	$1,053.18		$1,111.8266	$1,111.83	$1,111.85	$1,111.80