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	$169.85	3.402%	$175.6283	$175.63	$175.65	$175.60
Purchase #2	$72.63	7.282%	$77.9189	$77.92	$77.90	$77.90
Purchase #3	$104.61	6.802%	$111.7256	$111.73	$111.75	$111.70
Purchase #4	$43.53	7.254%	$46.6877	$46.69	$46.70	$46.70
Purchase #5	$244.52	4.851%	$256.3817	$256.38	$256.40	$256.40
Purchase #6	$36.61	13.290%	$41.4755	$41.48	$41.50	$41.50
Purchase #7	$120.27	5.712%	$127.1398	$127.14	$127.15	$127.10
7 purchase totals =	$792.02		$836.9575	$836.97	$837.05	$836.90