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	$167.66	10.707%	$185.6114	$185.61	$185.60	$185.60
Purchase #2	$40.46	8.398%	$43.8578	$43.86	$43.85	$43.90
Purchase #3	$149.32	7.714%	$160.8385	$160.84	$160.85	$160.80
Purchase #4	$83.56	5.774%	$88.3848	$88.38	$88.40	$88.40
Purchase #5	$238.84	12.342%	$268.3176	$268.32	$268.30	$268.30
Purchase #6	$218.85	8.477%	$237.4019	$237.40	$237.40	$237.40
Purchase #7	$174.74	9.436%	$191.2285	$191.23	$191.25	$191.20
7 purchase totals =	$1,073.43		$1,175.6405	$1,175.64	$1,175.65	$1,175.60