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	$145.76	4.287%	$152.0087	$152.01	$152.00	$152.00
Purchase #2	$157.60	6.174%	$167.3302	$167.33	$167.35	$167.30
Purchase #3	$53.91	13.336%	$61.0994	$61.10	$61.10	$61.10
Purchase #4	$218.40	12.559%	$245.8289	$245.83	$245.85	$245.80
Purchase #5	$81.96	13.852%	$93.3131	$93.31	$93.30	$93.30
Purchase #6	$218.69	9.450%	$239.3562	$239.36	$239.35	$239.40
Purchase #7	$175.40	5.580%	$185.1873	$185.19	$185.20	$185.20
7 purchase totals =	$1,051.72		$1,144.1238	$1,144.13	$1,144.15	$1,144.10