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	$118.69	7.626%	$127.7413	$127.74	$127.75	$127.70
Purchase #2	$77.64	4.114%	$80.8341	$80.83	$80.85	$80.80
Purchase #3	$216.71	7.361%	$232.662	$232.66	$232.65	$232.70
Purchase #4	$65.45	3.798%	$67.9358	$67.94	$67.95	$67.90
Purchase #5	$80.46	3.488%	$83.2664	$83.27	$83.25	$83.30
Purchase #6	$13.90	10.795%	$15.4005	$15.40	$15.40	$15.40
Purchase #7	$168.76	13.361%	$191.308	$191.31	$191.30	$191.30
7 purchase totals =	$741.61		$799.1481	$799.15	$799.15	$799.10