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	$141.90	7.127%	$152.0132	$152.01	$152.00	$152.00
Purchase #2	$66.91	9.315%	$73.1427	$73.14	$73.15	$73.10
Purchase #3	$19.43	5.736%	$20.5445	$20.54	$20.55	$20.50
Purchase #4	$98.28	7.531%	$105.6815	$105.68	$105.70	$105.70
Purchase #5	$127.54	13.408%	$144.6406	$144.64	$144.65	$144.60
Purchase #6	$62.27	4.773%	$65.2421	$65.24	$65.25	$65.20
Purchase #7	$134.48	8.132%	$145.4159	$145.42	$145.40	$145.40
7 purchase totals =	$650.81		$706.6805	$706.67	$706.70	$706.50