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	$48.44	11.361%	$53.9433	$53.94	$53.95	$53.90
Purchase #2	$129.98	3.461%	$134.4786	$134.48	$134.50	$134.50
Purchase #3	$205.73	3.360%	$212.6425	$212.64	$212.65	$212.60
Purchase #4	$243.54	7.400%	$261.562	$261.56	$261.55	$261.60
Purchase #5	$85.63	9.666%	$93.907	$93.91	$93.90	$93.90
Purchase #6	$86.54	4.356%	$90.3097	$90.31	$90.30	$90.30
Purchase #7	$212.45	3.824%	$220.5741	$220.57	$220.55	$220.60
7 purchase totals =	$1,012.31		$1,067.4172	$1,067.41	$1,067.40	$1,067.40